I am looking here for the best simple and intuitive application that is designed to produce neat looking graphs, for example "number of Ubuntu users in the last 10 years" or "average amounts paid by windows, mac and linux users for each Humble Indie Bundle edition".

I just want it to be easy to produce (not too many functions), and nice looking (no ugly business charts)!

"better" and "simple to use" are rather subjective so I'll post the one we use a lot! To quote a famous person: "There are no too complicated apps, user dependency overweighs"
–
RinzwindMay 30 '11 at 7:30

1

I usually use LibreOffice Calc or Graphviz.
–
AnonymousNov 22 '11 at 21:08

Can you export a single graph as an image (png, jpg, svg) from LibreOffice?
–
chtfnNov 23 '11 at 10:35

1

Yes, you can export to PNG, SVG and others. I am not sure what happens if you try export and you have graphs on different pages though.
–
AnonymousNov 25 '11 at 18:45

Although it is a library it is a very simple one.
You just start python interpreter and import the lib. For me it is simpler that most of spreadsheets plotters because I'm always getting lost in the gui.

RLPlot is is a plotting program to create high quality graphs from data. Based on values stored in a spreadsheet several menus help you to create graphs of your choice. The Graphs are displayed as you get them (wysiwyg). Double click any element of the graph (or a single click with the right mouse button) to modify its properties. RLPlot is a cross platform development for Linux and Windows. Mac OsX users can find some useful information how to install RLPlot at http://naranja.umh.es/~atg/.